Temperature indicator



o@ 14 1930. cfw. wYMAN 1,778,655

TEMPERATURE INDFCATOR A original Filed May 12D 1925 W /m lAar/)WPatented Oct. 14, 1930 UNITED STATES PATENT OFFICE CHARLES W. WYMAN, OFCLAREMONT, NEW HAMPSHIRE, ASSIGNOR T0 SULLIVAN MACHINERY COMPANY, ACORPORATION OF MASSACHUSETTS TEMPERATURE INDICATOR Application led May12, 1925, Serial My invention relates to temperature indicators and`more particularly to magnetic temperature indicators adapted to use inconnection with drill steels or other like article and having provisionfor indicating when the steel or other article has reached the desiredtemperature preparatory to the hardening process.

It is a well established fact that when the magnetism leaves the heatedsteel, that is, when the point of decalescence or critical point isreached, it is the proper time to quench the steel in the hardeningbath.

The main object of the present invention, therefore, is to provideimproved means for ascertaining with accuracy when the heated steel hasreached the point of decalescence. Another object of my invention is toprovide an improved temperature indicating device of exceedingly simpleand rugged character which may be manufactured at a minimum of expense.

In the preferred embodiment herein described, I have shown improvedtemperature indicating means of the magnetic type. Preferably, thisindicating means comprises a pivotally supported magnet of the permanenttype provided with novel means for providing the desired degree 0fresponsiveness to magnetic force and enclosed within a suitablenon-magnetic casing and having electric indicating means operated by theswinging movement of the magnet caused by.

the magnetism in the heated drill steel or other similar article.

In the accompanying drawings I have shown for purposes of illustrationone form which my invention may assume in practice.

In these drawings- Fig. 1 is a front view of an indicator constructed inaccordance with one embodiment of my invention, a portion of the casingbeing broken away to facilitate illustration.

Fig. 2 is a vertical sectional view taken substantially on line 2-'2 ofFig. 1 with a drill steel being yshown in dotted lines in operativeposition.

Fig. 3 is a transverse horizontal sectional view taken substantially online 3 3 of Fig. 1.

No. 29,809. Renewed March 12, 1930.

In this illustrative form of my invention I have shown an upstandingframe or casing 1 having a laterally extending support 2, hereinva planeshelf at its lower end and suitably attached thereto, herein formedintegral therewith, the lateral support 2 being adapted to support anarticle to be tested when laid horizontally thereon contiguous to animproved abutment and temperature indicating means carried by the frame1 and hereinafter more fully described.

Referring more particularly to the casing member 1, it will herein benoted that it is formed of a non-magnetic conducting material,preferably of brass, and provided with an interior chamber 3. Disposedsubstantially vertically in this chamber 3 is a magnet 4, herein of thepermanent horseshoe type, pivoted between its ends for a limitedmovement, as at 5, on a transverselydisposed rod or shaft 6 suitablysecured at its ends within the sides of the casing 1. It will herein benoted that the magnet 4 is formed of a piece of flat stock milled outcentrally a portion of its length in such manner as to form the polesthereof. As illustrated,this magnet has its poles 7 disposed at thelower end of the chamber 3 and movable on opposite sides of anupstanding partition or spacer member 8, herein likewise of non-magneticmaterial, formed on the back wall of the chamber 3 and projecting to thefront of the latter. The magnet is traversed by the rod 6 at a pointsubstantially off center, that is to say, the axis of the rod issubstantially nearer one surface, herein the rear one, of the magnetthan the other, and so the magnet, since the pivot is also below itscenter of gravity, normally tilts counterclockwise. As an importantfeature of the invention there is shown, in Figs. 1 and 2, securedadjacent the upper end of the magnet f1 as by a screw 9, a balancingpiece or weight 10, herein in the form of a stri of metal such as softspring steel, this weight permitting the proper variation in the degreeof unbalance of the magnet by bending the piece 10 towards or from itthereby altering the center of gravity. The screw 9 serves as a stop tokeep the magnet from tilting further counterclockwise. In the positionindicated in Fig. 2, the center of gravity of the magnet lies to oneside of the vertical plane including the magnet pivot and the magnet ismovable to lessen the distance between its center of gravity and thevertical plane including the pivotal axis when influenced by a bodyofmagnetic material.

It will herein be observed that the upper end of the magnet 4 has formedthereon an upwardly extending extension or lug 11 having threadedlysecured therein a suitable brass bushing 12 and this bushing in turn hasthreadedly secured therein an adjustable screw 13. The screw 13 isconnected by means of a conductor wire 14 with a suitable terminal plug15 and this screw forms an electrical contact member which is adapted tocooperate with an electrical contact member 16. The contact member 16 isconnected by means of a strip of conducting material 17, which isdisposed within a transverse slot 18 formed within a strip of insulatingmaterial 19, to a suitable terminal plug 2() and these terminal plugs 15and 20 are connected by means of conductor wires 21 and 22 to suitableindicating means herein in the form of an electric light, not shown.Herein, it will be noted that a cover 23 seals the chamber 3 and isattached to the casing member 1 by suitable means such as screws'24 andremovable to permit access to the parts inside the chamber wheneverdesired. It will also be noted that herein the lower end of the cover 23presents an upstanding abutment 25 of non-magnetic conducting materialfor the articles to be tested, although obviously a separate abutmentplate may be utilized if desired. Attention also is directed to the factthat the abutment 25 is engaged and braced by the partition member4 8 insuch manner as to prevent damage thereto.

In the operation of my improved temperature indicator it will be evidentthat when it is desired to determine the temperature of a drill steel orthe like under treatment in a furnace, it is only necessary to place theend of the steel on the support 2 with its extremity preferably closelyadjacent the lower outer surface of the upstanding abutment 25, asindicated by dotted lines in Fig. 2. With the article to be tested inthis position, if the temperature has not reached the desired point, i.e. that at which the steel loses its magnetic quality, vthe magnet 4will be attracted, and will swing about its pivot toward the steel, thusmoving the contact member 13 toward the right in Fig. 2, and therebyengaging the cooperating Contact member 16, consequently causing acircuit between the conductor wires 21 and 22 to be closed and lightingthe indicator light so as to advise the operator that further heating isnecessary preparatory to the hardening process. If, however, the steelhas reached the point of decalescence or critical point, i. e. when theheated steel loses its magnetic quality, the contact between the members13 and 16 will not be made and the light not lighted. The operator willthen know that no further heating is necessary and that the steel is ofproper temperature to be quenched in the hardening bath. It will hereinalso be noted lthat the balancing piece oi weight 10 may be adjusted toinsure the proper position of the center of gravity of the magnet'withfacility by merely bending the iiexible metal in# wardly or outwardly asdesired.

As a result of my improvement it is made possible to obtain greatercertainty of the tem erature of the steel preparatory to the har eningoperation. It will also be noted that the entire mechanism while totallyen closed is readily accessible whenever desired to permit replacementor repair and that the indicator mechanism while exceedingly acJ curateis of such a simple and rugged mechanical character as to permit it tobe kept in repair by the average furnace operator or repair man. It willstill further be noted that an improved temperature indicating device isprovided which is of exceedingly simple and rugged character which may emanufactured at a minimum of expense.

While I have in this application specilically described one form whichmy invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinv/en tion may be modified and embodied in various carried by saidmagnet at its upper end above its pivot for shifting the center ofgravity 'to secure proper responsiveness to magnetic bodies.

2. A magnetic temperature indicator including a magnet, means forpivotally supporting the same, means engageable with the magnet tomaintain the latter 1n a position in which its center of gravity isoffset toward the front part of the indicator from a vertical planeincluding its axis of pivotal movement,

means for varying the force necessary to et feet pivotal movementcansinor the center of gravity to approach said vertical plane, andcontrolling means carried by said magnet adapted to control an indicatorupon pivotal UHD movement of said magnet causing the center of gravityof the latter to approach said vertical plane.

3. A magnetic temperature indicator coms prising a substantia 1yvertically disposed magnet pivoted about an axis which lies below itscenter of gravity and oset toward the rear of the indicator from avertical plane including the center of-gravity of the magnet,

lo means for normally maintaining said magnet in a position with itscenter of gravity spaced a predetermined distance from a vertical planepassing through the axis of pivotal movement of the magnet, andindicating u means governed by said magnet when the latter is swung fromits first mentioned position.

4. A magnetic temperature indicator comprising a substantiallyvertically disposed ,o magnet pivoted about an axis below its center ofgravity and offset toward the rear of the indicator from a verticalplane passing through the center of gravity and to whic the axis ofpivotal movement is parallel,

25 means for normally maintaining said magnet in a certain position,indicating means adapted to be operated by said magnet when the latteris swung out of said position, and means for adjusting the position ofsaid center of au gravity relative to the pivotal axis.

5. In a magnetic temperature indicator, a permanent magnet, means forpivotally supporting the same at a point o'set from its center ofgravity, a stop limiting the move- 35 ment of said magnet which resultsfrom the offsetting of its center of gravity from its pivot point, meansfor varying the locus of the center of gravity of said magnet withrespect to said stop and pivot to regulate the force o required to swingsaid magnet toward a po-v sition in which the pivot and center ofgravity thereof lie in the same vertical plane and other means carriedby said magnet an controlled by the movements thereof for governing theoperation ofthe indicator.

In a magnetic temperature indicator, a frame, a magnet mounted forswinging movement therein about an axis offset from its ceni ter ofgravity, a stop carried by the frame o for normally maintaining saidmagnet in a predetermined position with its center of gravity and itspivot in parallel vertical planes, means for positioning an article ad-]acent said vmagnet at a point where a mag- 55 netic force will causesaid magnet to be swung away from said stop, an adjustable weightcarried by said magnet for varying the force required to swing saidmagnet away from its stop, and other means controlled by the moveo mentof saidma et for controlling the operation of an in icator.

In testimony whereof I airix my signature.

CHARLES W. WYMAN.

